Control for a steam generator



Feb. 4, 1969 -r. F. cooK ET AL I CONTROL FOR A STEAM GENERATOR Sheet Filed Dec. 16, 1966 INVENTORS THOMAS F. COOK STANLEY Ev msc zfi BY fill).-

ATTO RNEY Feb. 4, 1969 F,'CQOK ETAL CONTROL FOR A STEAM GENERATOR Sheet Filed Dec. 16, 1966 INVENTORS THOMAS F. COOK P R M T O 7W WW C U N B E I l l I I I Ir II II i 6 L I 5 w m 4 m w G m R 2 W \l E F 9 G 2 C 3 TN EH HC X 1 E I 7 w w 4 a D. Y M w m Hu /4 Dr 1 P 2 U S\ m A w m P P P P I. U U 2 5 5L R\|/\5 E 2 E T U A F W STANLEY E. DYB Z BY ,4

ATTORNEY F l G. 5

United States Patent 3,425,622 CONTROL FOR A STEAM GENERATOR Thomas F. Cook, Arlington Heights, and Stanley E.

Dybczak, Chicago, Ill., assignors to Vapor Corporation, Chicago, 11]., a corporation of Delaware Filed Dec. 16, 1966, Ser. No. 602,335 U.S. Cl. 23625 Claims Int. Cl. F22b 35/00 ABSTRACT OF THE DISCLOSURE This invention relates in general to a control for a steam generator, and more particularly to a control for metering air and fuel in response to feedwater requirements, and still more particularly to a diaphragmrless control that is relatively insensitive to water surges or pulses and which maintains the same calibration throughout its life.

The control of the present invention is arranged in the feedwater line to the coil of a steam generator to be responsive to the feedwater flow rate :and operable to meter the air and fuel to the burner of the steam generator. Fuel and air are therefore metered to the boiler by the control in direct proportion to the amount of feedwater flowing through the control to the boiler or steam generator. The control includes a body having a chamber therein with an inlet and an outlet to be connected to the feedwater line. A metering cylinder is arranged within the body between the inlet and outlet and having a piston slidable therein in driving engagement with a lever for controlling the air and fuel rate to the steam generator. A metering orifice or opening is provided in the metering cylinder that co acts with the piston so that a given flow rate of feedwater will effect a given movement of the piston and ultimately a given flow rate of air and fuel to the steam generator. Attached to the piston is a dampening disc which meets therewith at the inlet to dampen water surges and pulses that may be generated in the feedwater line.

Heretofore, controls for controlling the rate of fuel and airflow to a steam generator in response to feedwater flow have employed rubber diaphragms. Because of a need to connect a heat exchanger ahead of such controls, feedwater forced through such controls is hot. Because hot water and water contaminants are detrimental'to a rubber diaphragm, maintenance on such a control has been costly. Further, subjecting a rubber diaphragm to hot water causes stretching thereof and the resulting reduction in the effective area of the diaphragm and a change in calibration.

Therefore, it is an object of the present invention to obviate the above named difiiculties and toprovide a new and improved control for steam generators for controlling the metering of air and fuel in response to feedwater flow rate.

Another object of the present invention is in the provision of a control for a steam generator that regulates the metering of air and fuel in response to feedwater flow rate which eliminates the heretofore used diaphragm that is subject to premature failure and stretching due to excessively high temperatures of feedwater and water contaminants, thereby reducing maintenance and the need for calibration changes.

A still further object of the present invention is in the provision of a control for steam generators that meters air and fuel in direct proportion to feedwater flow rate which is relatively insensitive to water surges or pulses generated in the feedwater line.

Other objects, features, and advantages of the invention "ice will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts, in which:

FIG. 1 is a sectional view of the control according to the present invention shown as applied to an air and fuel regulating device, wherein the parts as shown in solid line are positioned where no pressure of feedwater flow rate exists and the parts shown in phantom illustrate a position where a given feedwater flow rate is in the feedwater line;

FIG. 2 is a detail view, partly fragmentary and taken substantially along line 22 of FIG. 1;

FIG. 3 is a bottom plan view of the metering cylinder taken substantially along line 3"-3 of FIG. 1 and looking in the direction of the arrows;

FIG. 4 is a side elevational view of the metering cylinder, and taken substantially along line 4-4 of FIG. 1 and looking in the direction of the arrows; and

FIG. 5 is a block diagram of a steam generator employing the control of the present invention.

Referring now to the drawings, and particularly to FIG. 1, the control of the present invention is generally designated by the numeral 10 and illustrated in association with an air and fuel regulating or metering device 11 that responds to the operation of the control and the feedwater flow rate to meter the air and fuel to a steam generator.

Application of the invention to a steam generator is illustrated by the block diagram of FIG. 5. A steam generator 12 includes a coil 13 and a burner 14. A feedwater line 15 delivers feedwater to the coil, while an air-fuel line 16 delivers air and fuel to the burner 14. The feedwater line 15 passes through the control 10 of the present invention as does the air-fuel line 16, wherein the rate of air and fuel supplied to the burner is directly proportional to the rate of feedwater supplied to the coil. Air is supplied to the control through an air line 17 that is suitably connected to an air supply 18, while fuel is supplied to the control through a fuel line 19 connected to a pump 20 and a fuel supply 21. It is not intended that the air and fuel be mixed by the control, but for purposes of clarity, only a single air-fuel line 16 is shown between the control and the burner. A feed- Water line 22 supplies feedwater to the control from a heat exchanger 23 that raises the temperature of the feedwater pumped thereto by a pump 24 from a suitable feedwater supply 25.

Referring again generally to FIG. 1, the control 10 includes a body or casing 26 having an upper section 27 and a lower section 28 suitably connected by bolts 29 and provided therebetween with a sealing gasket 30. A chamber is defined within the body 26 that includes an upper chamber section 31 and a lower chamber section 32. A feedwater inlet 33 directly communicates with the lower chamber section, while a feedwater outlet 34 directly communicates with the upper chamber section 31, whereby the inlet and outlet are connected into the feedwater line ahead of the coil. While the lower section of the body is originally made open at its lower end, a cylinder cover 35 closes the lower end but provides ac cess to the lower chamber section 32 if so desired.

A metering cylinder 36 is arranged between the upper and lower chamber sections, and is threaded at 37 to be threadedly mounted on a necked-down portion 38 of the lower body section 28. In order to facilitate mounting of the metering cylinder in the lower body section, the lower end is hexagonally formed at 39, FIG. 3, to receive a Wrench, and by virtue of a radial flange 40 above the hexagonal portion, the metering cylinder 36 may be precisely mounted by running the cylinder in until the flange abuts the necked-down portion 38.

A bore 41 is formed in the metering cylinder 36 and slidably receives a piston 42, both of which coact with a metering opening 43 formed in the metering cylinder to provide a given piston movement for a given feedwater flow rate through the control. As shown in solid lines in FIG. 1, the piston 42 is positioned so that no feedwater flow may pass from the lower chamber section 32 to the upper chamber section 3-1 inasmuch as the piston is below the lower edge of the metering opening 43. As the piston moves upwardly due to the increase of the feedwater flow rate, it gradually exposes the metering opening 43 whereby the flow rate through the control upwardly from the lower chamber section 32 through the metering opening 43 and the upper chamber section 31 effects a precise positioning of the piston 42. The piston shown in dot-dash lines is at a position where the flow rate has caused it to move and where intercommunication between the upper and lower chambers is established. Thus, the feedwater will enter the inlet 33 and flow upwardly through the chamber section 32, through the opening 43, the chamber 31 and out the outlet 34 and onto the coil of the steam generator.

While the metering opening 43 is illustrated as a straight slot in FIG. 4, it should be appreciated that it could be otherwise shaped, such as being tapered in either direction or oval, or could even consist of one or more holes. If a plurality of holes are employed to define the metering opening, the holes may be axially aligned, helically aligned, or at random in any position that would effect the desired purpose of the metering opening. A slot could also be arranged in a helical fashion rather than being axial as shown in FIG. 4. In any event, the metering opening is critical so that it must be sized to allow a given piston movement for a given feedwater flow rate so that the air and fuel metering established by the control is in proper proportion to the feedwater flow rate to give proper operation of the steam generator.

Dampening of water surges or pulses generated in the vfeedwater line and generally by the water pump is performed by a damper assembly 44 located in the lower chamber section 32. The assembly includes a damper rod 45 secured to the piston 42 at its upper end and having secured thereto at its lower end a dampening .piston or disc 4'6. The disc 46 is sized to freely move within the chamber section 32, while the length of the damper rod 44 is such as to space the dampening disc 46 adjacent to the bottom of the chamber section 32 when the piston is in closed position as shown in FIG. 1. Dampening of the water surges or pulses prevents unnecessary wear on the moving parts. A surge or pulse results in substantially no movement or force on the piston 42 for movement of same inasmuch as the surge or pulse hits the top surface of the dampening disc and the lower surface of the piston 42. Thus, water flow pulsation on the piston operation and movement is substantially eliminated. It should also be appreciated that the dampening disc 46 is always immersed in a supply of water in the lower chamber section 32. In order to eliminate sto page of water flow when the dampening disc 46 is in its uppermost position and against the metering cylinder 36, openings 47 in the form of notches are provided in the hexagonal section 39.

The damper rod 45 is connected to the piston 42 by means of a diammetrically reduced portion 48 that extends through a bore 49 in the piston, and which threadedly receives at its outer end a pivot cap 50. Shims 51 and 52 are provided on opposite sides of the piston, wherein the relative position of the piston may be altered by adding or removing a shim from either side. If a shim is added below the piston, one must be removed from above the piston, and similarly, if a shim is added above the piston, one must be removed from below the piston in order to maintain the assembled height of the damper assembly to maintain the correct starting position, The piston 42 and the metering cylinder 36 are made of such materials as to provide long wearing characteristics.

Movement of the piston 42 is imparted to the air and fuel metering device 11 by a yoke 53 and a lever 54. The lower end of the yoke 53 includes a concave socket 55 engaging a convex head 56 formed on the upper end of the pivot cap 50, whereby pivotal movement may exist between the yoke and the piston. The upper end of the yoke 53 includes a bearing 57 bearingly engaging a stub shaft or pin 58 extending laterally from the lever 54. A second stub shaft or pin 59 extends laterally from the opposite end of the lever 54 and is bearingly received in a boss '60 and suitably connected to the air and fuel metering device 11 to operate same in response to movement effected thereby from movement of the piston 42, the yoke 53 and the lever 54. A torsion spring 61 is suitably mounted within the air and fuel metering device 11 to continually exert a biasing force in one direction through the lever 54 to the shaft 59. The biasing force is transmitted through the lever 54 and the yoke 53 to the piston 42 and is in the direction to urge the piston 42 downwardly. Thus, yoke movement is restricted by its mechanical connection to the torsion spring 61, and when the upward force of the feedwater on the piston 42 is greater than the downward force of the torsion spring on the yoke, the piston will move upwardly. Upward movement of the piston continues until the upward .force of the feedwater on the piston equals the downward force of the torsion spring on the yoke.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention, but it is understood that this application is to be limited only by the scope of the appended claims.

The invention is hereby claimed as follows:

1. In a steam generator having a burner and a coil, the improvement in a control for metering the air and fuel to the burner in response to the feedwater flow to the coil, said control comprising a body having a chamber therein, a feedwater inlet and a feedwater outlet to said chamber, a metering cylinder in said chamber between the inlet and outlet, a piston slidable in said cylinder having one side in communication with the feedwater flow at the inlet and the other side in communication with the feedwater flow at the outlet, metering opening means along said cylinder for communicating the inlet and outlet during a given feedwater flow rate and to provide a given movement of said piston for a given flow rate, a dampening assembly connected to said piston at the inlet side and responsive to the feedwater at the inlet to dampen feedwater surges, and lever means operated by said piston to control the air and fuel metering to the burner.

2. In a steam generator as defined in claim 1, wherein said metering opening means includes a slot extending along the cylinder.

3. In a steam generator as defined in claim 2, wherein said slot is straight and extends parallel to the axis of the cylinder.

4. In a steam generator as defined in claim 1, wherein said dampening assembly includes a rod extending from the piston having a dampening disc mounted thereon.

5. A control for metering the air and fuel supply to a steam generator in response to the feedwater requirements thereof, said control comprising a body having a chamber therein, an inlet and an outlet to said chamber adapted to be connected in a feedwater line so that the feedwater flow traverses said chamber, a metering cylinder in said chamber arranged between the inlet and outlet, a piston slidable in said cylinder and dn'vingly connected on one end to air and fuel metering means, said piston having one end exposed to the outlet end of the chamber and the other end exposed to the inlet end of the chamber, metering opening means along said cylinder intercommunicating the inlet and outlet during a given feedwater flow rate and to provide a given piston movement and actuation of the air and fuel metering means for a given feedwater flow rate, and a dampening rassembly drivingly connected to said piston for dampening feedwater surges or pulses at the inlet end of the chamber, said piston and said dampening assembly being in conjoint communication with the feedwater at the inlet.

6. A control as defined in claim 5, wherein said metering opening means includes a straight slot extending parallel to the axis of the cylinder.

7. A control as defined in claim 6, wherein said dampening assembly includes a rod having a dampening disc mounted thereon.

8. A control as defined in claim 7, wherein said air and fuel metering means is connected to the outlet end of said piston and said dampening assembly is connected to 15 the inlet end of the piston.

9. A control as defined in claim 8, wherein means is provided to exert a resilient force against piston movement by the feedwater flow.

10. A control as defined in claim 7, wherein the dampening disc is sized to be freely movable in said chamber.

References Cited UNITED STATES PATENTS 629,176 7/1899 Schlumberger 2362S 1,370,765 3/1921 Powell 23625 1 2,164,323 7/1939 Hahn 236-25 2,184,399 12/1939 Powell 23625 FOREIGN PATENTS 528.713 11/ 1940 Great Britain.

EDWARD J. MICHAEL, Primary Examiner. 

